The saturation or chroma of a hue defines its intensity or purity . Terms like "weak", "strong", "brilliant", or "vivid" are often used to describe saturation.

A contrast control determines saturation: decreasing contrast adds tone (gray), while increasing contrast adds more of the hue.

Decreasing contrast adds tone and brings a color closer to gray.
CHART: Color wheel before decreasing contrast CHART: Color wheel after decreasing contrast 1 time CHART: Color wheel after decreasing contrast 2 times CHART: Color wheel after decreasing contrast 3 times

Increasing contrast adds more of the hue to the color, making it more brilliant, i.e. pure hue. In the computer RGB system, this means a color would come closer to one of 8 (2^3) possible pure colors: Red, Yellow, Green/Lime, Cyan/Aqua, Blue, Magenta/Fuchsia, White, or Black.
CHART: Color wheel before increasing contrast CHART: Color wheel after increasing contrast 1 time CHART: Color wheel after increasing contrast 2 times CHART: Color wheel after increasing contrast 3 times

CHART: Web Safe colors before increasing contrast 0%

CHART: Web Safe colors after increasing contrast by 25% 25%

CHART: Web Safe colors after increasing contrast by 50% 50%

CHART: Web Safe colors after increasing contrast by 75% 75%

CHART: Web Safe colors after increasing contrast by 100% 100%

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